The present invention relates to a process for producing a coated glass and coated glasses produced by the process. In particular, the present invention relates to a process for sputter coating glass with up to three or more reflective metal layers.
Glass coatings for low emissivity and/or for solar control may be deposited by physical vapour deposition processes, for example, sputtering. Sputtered low emissivity and solar control coating stacks are commonly made up of repeat sequences of substrate/base dielectric layer sequence/(Ag/dielectric layer sequence)n with each of the n dielectrics not necessarily having the same thicknesses or composition. It is becoming more common in the industry for n to equal 2 or even 3. As dielectric layers are thicker and slower to deposit than metal layers, this requires a large number of cathodes in a production coating plant.
Previously large complicated coating stacks have required extensions to coating plants to get the sufficient number of cathodes to make the different materials in sufficient number and order. Extra pumping sections have to be included in the extension to allow the multiple reactive processes to run in sequence. This is done at great expense and with huge disruption, as the coating line needs to be stopped for an extended period for engineering installation. Each new cathode and pumping section also requires the accompanying power supply, vacuum pumps, conveyor sections, services, instrumentation and integration into the control system. It is also likely to cause restructuring of the downstream logistics and possibly even new civil works or building extension. As triple (n=3) stacks become more common, these problems are likely to grow.
It is an aim of the present invention to address the problems with the prior art.